URAT: First USNO Robotic Astrometric Telescope Star Catalog

URAT is a follow-up project to the UCAC catalog, using the same astrograph but with a larger focal plane array and a redder bandpass. Longer integration times and more sensitive CCDs resulted in a 4-fold increase in the average number of stars per square degree compared to UCAC, with positional precision improved through multiple sky overlaps per year. The catalog, published by the National Aeronautics and Space Administration, includes observations of stars as bright as about 3rd magnitude via an objective grating.

Use Cases

• Precise star position measurement based on improved positional precision from multiple sky overlaps.
• Astrometric calibration of other surveys using the catalog's high-density star positions.
• Studying bright stars (down to ~3rd magnitude) based on the extended dynamic range from the objective grating.
• Comparing stellar density and limiting magnitude with previous UCAC survey data.

Strengths

• Average number of stars per square degree is about 4 times greater than the preceding UCAC catalog.
• Positional precision is significantly improved compared to UCAC due to multiple sky overlaps per year.
• Dynamic range extends to include observations of stars as bright as about 3rd magnitude.

Limitations

• Column-level documentation is absent; field semantics must be inferred after download.
• Row count is unknown, which may limit suitability assessment.

Provenance

Source

National Aeronautics and Space Administration

Collection Method

Observations from the USNO Robotic Astrometric Telescope, a follow-up to the UCAC project.

Freshness

Last updated 2026-03-13 16:36:26.090410; freshness should be verified.